The present invention relates to a power supply system which steps down a power having a high voltage.
A multi-voltage power supply system having a high voltage system and a low voltage system is proposed recently for a vehicle.
xe2x80x9cAutomotive electronics power upxe2x80x9d of IEEE SPECTRUM, May 2000 discloses a multi-voltage power supply system for a vehicle.
It is an object of the present invention to provide a multi-voltage power supply system for stepping down a power having a high voltage.
It is another object of the present invention to allow the multi-voltage power supply system to supply a power (having a properly lowered voltage) to a low voltage load, even when a low voltage transistor is in failure, thus saving the need of a low voltage battery.
According to a first aspect of the present invention, there is provided a power supply system comprising:
1) a high voltage power supply for supplying a power having a high voltage;
2) a main power supply wire connecting to the high voltage power supply;
3) a step down circuit comprising the following operations:
a) inputting, by way of the main power supply wire, the power having the high voltage,
b) stepping down the thus inputted power having the high voltage, and
c) outputting a power having a lowered voltage lower than the high voltage, a first predetermined voltage being defined lower than the lowered voltage stepped down by the step down circuit;
4) a sub-power supply wire connecting the high voltage power supply to an output side of the step down circuit;
5) a voltage sensor for sensing a voltage of the power outputted from the step down circuit;
6) a sub-switching element disposed on the sub-power supply wire; and
7) a controller for controlling the sub-switching element,
a) the controller turning off the sub-switching element, when the voltage sensed with the voltage sensor is equal to or higher than the first predetermined voltage; and
b) the controller driving the sub-switching element in duty control for stepping down the power having the high voltage to the power having the lowered voltage outputted from the step down circuit, when the voltage sensed with the voltage sensor is lower than the first predetermined voltage.
According to a second aspect of the present invention, there is provided a power supply process comprising:
1) supplying, from a high voltage power supply, a power having a high voltage;
2) stepping down the power having the high voltage, the stepping down operation by a step down circuit comprising the following operations:
a) inputting, by way of a main power supply wire connecting to the high voltage power supply, the power having the high voltage,
b) stepping down the thus inputted power having the high voltage, and
c) outputting a power having a lowered voltage lower than the high voltage, a first predetermined voltage being defined lower than the lowered voltage thus stepped down;
3) sensing a voltage of the power outputted from the step down circuit; and
4) controlling a sub-switching element disposed on a sub-power supply wire which connects the high voltage power supply to an output side of the step down circuit, the controlling operation comprising the following operations:
a) turning off the sub-switching element, when the voltage thus sensed is equal to or higher than the first predetermined voltage; and
b) driving the sub-switching element in duty control for stepping down the power having the high voltage to the power having the lowered voltage outputted from the step down circuit, when the voltage thus sensed is lower than the first predetermined voltage.
According to a third aspect of the present invention, there is provided a power supply system comprising:
1) a supplying means for supplying a power having a high voltage;
2) a first connecting means connecting to the high voltage power supply;
3) a stepping down means comprising the following operations:
a) inputting, by way of the first connecting means, the power having the high voltage,
b) stepping down the thus inputted power having the high voltage, and
c) outputting a power having a lowered voltage lower than the high voltage, a first predetermined voltage being defined lower than the lowered voltage stepped down by the stepping down means;
4) a second connecting means connecting the high voltage power supply to an output side of the stepping down means;
5) a sensing means for sensing a voltage of the power outputted from the stepping down means;
6) a sub-switching means disposed on the second connecting means; and
7) a controlling means for controlling the sub-switching means,
a) the controlling means turning off the sub-switching means, when the voltage sensed with the sensing means is equal to or higher than the first predetermined voltage; and
b) the controlling means driving the sub-switching means in duty control for stepping down the power having the high voltage to the power having the lowered voltage outputted from the stepping down means, when the voltage sensed with the sensing means is lower than the first predetermined voltage.
According to a fourth aspect of the present invention, there is provided a power supply system comprising:
1) a high voltage power supply for supplying a power having a high voltage;
2) a main power supply wire connecting to the high voltage power supply;
3) a step down circuit comprising the following operations:
a) inputting, by way of the main power supply wire, the power having the high voltage,
b) stepping down the thus inputted power having the high voltage, and
c) outputting a power having a lowered voltage lower than the high voltage, a first predetermined voltage being defined lower than the lowered voltage stepped down by the step down circuit, a second predetermined voltage being defined higher than the lowered voltage stepped down by the step down circuit;
4) a sub-power supply wire connecting the high voltage power supply to an output side of the step down circuit;
5) a voltage sensor for sensing a voltage of the power outputted from the step down circuit;
6) a main switching element disposed on the main power supply wire;
7) a sub-switching element disposed on the sub-power supply wire; and
8) a controller for controlling the main switching element and the sub-switching element,
a) the controller turning on the main switching element while the controller turning off the sub-switching element, when the voltage sensed with the voltage sensor is in both of the following states:
i) equal to or lower than the second predetermined voltage, and
ii) equal to or higher than the first predetermined voltage;
b) the controller driving the main switching element in duty control for stepping down the power having the high voltage to the power having the lowered voltage outputted from the step down circuit, when the voltage sensed with the voltage sensor is higher than the second predetermined voltage; and
c) the controller driving the sub-switching element in duty control for stepping down the power having the high voltage to the power having the lowered voltage outputted from the step down circuit, when the voltage sensed with the voltage sensor is lower than the first predetermined voltage.
According to a fifth aspect of the present invention, there is provided a power supply system comprising:
1) a high voltage power supply for supplying a power having a high voltage;
2) a main power supply wire connecting to the high voltage power supply;
3) a step down circuit comprising the following operations:
a) inputting, by way of the main power supply wire, the power having the high voltage,
b) stepping down the thus inputted power having the high voltage, and
c) outputting a power having a lowered voltage lower than the high voltage, a first predetermined voltage being defined lower than the lowered voltage stepped down by the step down circuit, a second predetermined voltage being defined higher than the lowered voltage stepped down by the step down circuit;
4) a sub-power supply wire connecting the high voltage power supply to an output side of the step down circuit;
5) a voltage sensor for sensing a voltage of the power outputted from the step down circuit;
6) a main switching element disposed on the main power supply wire;
7) a sub-switching element disposed on the sub-power supply wire; and
8) a controller for controlling the main switching element and the sub-switching element,
a) the controller turning on the main switching element while the controller turning off the sub-switching element, when the voltage sensed with the voltage sensor is in both of the following states:
i) equal to or lower than the second predetermined voltage, and
ii) equal to or higher than the first predetermined voltage; and
b) the controller turning off the main switching element while the controller driving the sub-switching element in duty control for stepping down the power having the high voltage to the power having the lowered voltage outputted from the step down circuit, when the voltage sensed with the voltage sensor is in at least one of the following states:
i) higher than the second predetermined voltage, and
ii) lower than the first predetermined voltage.
According to a sixth aspect of the present invention, there is provided a power supply system comprising:
1) a high voltage power supply for supplying a power having a high voltage;
2) a main power supply wire connecting to the high voltage power supply;
3) a step down circuit comprising the following operations:
a) inputting, by way of the main power supply wire, the power having the high voltage,
b) stepping down the thus inputted power having the high voltage, and
c) outputting a power having a lowered voltage lower than the high voltage, a second predetermined voltage being defined higher than the lowered voltage stepped down by the step down circuit;
4) a voltage sensor for sensing a voltage of the power outputted from the step down circuit;
5) a main switching element disposed on the main power supply wire; and
6) a controller for controlling the main switching element, the controller driving the main switching element in duty control for stepping down the power having the high voltage to the power having the lowered voltage outputted from the step down circuit, when the voltage sensed with the voltage sensor is higher than the second predetermined voltage.
The other objects and features of the present invention will become understood from the following description with reference to the accompanying drawings.